Advances in recombinant DNA technology have provided a wide variety of tools for protein production and purification in sufficiently large quantities for use as drugs. However, proteins are prone to undergo physical or chemical changes in liquid or even lyophilized formulations, including denaturation, formation of soluble and insoluble aggregates, hydrolysis, or oxidation. These changes often lead to the loss or reduction of the pharmaceutical activity of the protein of interest. To date, the stabilization and preservation of recombinant proteins in liquid or lyophilized formulations remain a challenge.
The fibroblast growth factors (FGFs) are a family of growth factors that bind to proteoglycans. These growth factors are potent mitogens that are essential to the growth and differentiation of the cells involved in wound healing. Fibroblast growth factor 2 (FGF-2) is a heparin-binding growth factor that belongs to this family. FGF-2 has pleiotropic roles in multiple tissue and cell types, including its mitogenic, angiogenic, and survival factor activities. FGF-2 is involved in cell migration, cell differentiation, and in a variety of developmental processes. Its therapeutic potential has been examined in clinical trials involving wound healing and treatment of ischemic cardiovascular diseases.
Although early pharmaceutical preparations of FGF-2 were shown to be biologically active through in vitro cell assays, these formulations produced heterogeneous mixtures after short-term storage at room temperature, under refrigeration, or in the frozen state. In addition, insoluble aggregates can form in aged solution formulations at higher FGF-2 concentrations (1 mg/ml or greater) and in lyophilized formulations. Methods for preparing stabilized FGF-2 formulations have been under pursuit. See, for example, U.S. Pat. Nos. 5,217,954, 5,202,311, 5,130,418; and PCT Publication WO 92/01442. As oxidation is one of the major destructive processes contributing to FGF-2 instability, formulations that reduce FGF-2 oxidation are needed.